In network communications, the term “multicast” generally refers to transmitting data to multiple receivers simultaneously using a single transmission stream from a source. Multicast may be contrasted with unicast, which involves transmitting data to the multiple receivers using separate transmission streams from the source for each receiver. Multicast is also distinct from broadcast, which entails transmitting data to every node within reach on the network, rather than to a list of specific nodes, as in multicast.
By sending only a single transmission stream intended for multiple receivers (e.g., using a multicast address for addressing a group of receivers), multicast conserves bandwidth compared to unicast. Thus, multicast is often used in streaming media applications, such as Internet television or streaming digital audio, as well as in a variety of other Internet Protocol (IP) applications.